It is desirable to test circular saws at the point of manufacture, for example, in order to avoid the sale and delivery of saws having characteristics which are unacceptable for their intended operation, or at the point of use in order to determine if previously acceptable characterstics thereof have been retained over the period of time. Further, even for saws acceptable for sale and use, it is desirable to retain an historical record of the characteristics thereof for future reference as, for example, to compare a particular saw's characteristics over time or to provide information for a statistical analysis of the charactertistics of a large number of different saws for future design reference purposes.
It is, of course, desirable that saws during operation cut in a narrow straight line with minimal, ideally zero, deviation from a cutting plane. Such deviations can arise if the overall saw blade is not perfectly flat, i.e., the saw blade curves out of an ideal flat plane, a condition sometimes referred to as "cupping" or "dishing" because of the shape the saw blade assumes during rotation. When the saw blade is substantially flat, i.e., all portions thereof lie in the cutting plane during rotation, particuarly at the saw's design operating speed, the saw is said to be fully "developed".
A further problem arises when the saw blade during operation moves at a relatively slow rate in a lateral, or side-to-side, direction about the desired cutting plane, such movement often being referred to as a "wobble". It is desirable to minimize the amplitude of the wobble so that the cut deviates as little as possible from the desired cutting plane, that is a straight cut occurs. Further, it is desirable that the cutting plane of the saw blade be maintained perpendicular to the axis of rotation during operation. Moreover, it is desirable that relatively high frequency excursions of the cutting edge about the cutting line be minimized so that the width of the cut is minimized. It is helpful, therefore, to test certain saw blade characteristics under various conditions in order to predict the extent to which a saw will avoid such problems during operation.
One characteristic that has been used by those in the art for such purpose has been the wobble that exists at a relativley low speed of rotation. In accordance therewith, a contact sensor, such as a position gauge, is placed against the lateral surface of the saw, usually near the cutting edge thereof, and the movement of the dial of the gauge is observed so as to determine the lateral movement of the surface about a mean, or reference, value as the saw is relatively slowly rotated manually on a test spindle. While such visual inspection process may provide some indication of the wobble and to some extent the flatness of the saw blade at such rotating speed, such a technique does not provide a sufficiently accurate tracking of such movement so as to effectively predict the operation of the saw at the operating speed of rotation during use.
It is desirable to provide better testing procedures which significantly improve the ability to establish suitable criteria for a saw's operating characteristics, as well as to determine such characteristics for particular saws for comparison with such criteria. Such testing procedures would permit a more accurate prediction of the saw's potential adequacy of performance during use so that saws not satisfying such criteria can be suitably detected and the saw either reworked or rejected before sale and delivery to a customer or so that the performance of saws already in use can be periodically rechecked.